Raising a WWII Bomber From the Depths of the Ocean

Archaeology is not, in general, a thrilling and exciting pastime. But sometimes, gently moving dirt around with paintbrushes gives way to something more adrenelaine-pumping -- in this case, trying to raise a rusted and rotting German bomber from the depths of the English Channel, without the whole thing falling to bits.

Monday 26th August, 1940, started as another day in the Battle of Britain. RAF bombers had executed the first raid on Berlin the night before, and the Luftwaffe were out for revenge. The twin-engined Dornier bombers allotted to the German Air Force's 7th Squadron were part of the counterattack, tasked with hitting Debden and Hornchurch airfields.

One Dornier didn't make it, though. Flying above the clouds short of the English coast, Dornier 5KAR was separated from the rest of the pack, and set on by RAF Boulton Paul Defiants. Both engines and the cockpit were hit, and the Dornier was forced to crash-land on the Goodwin Sands, just off the coast of Kent, at low tide. The surviving crew were rescued, and the wreck was forgotten about.

Shift forward 60 years, and a recreational diver stumbled across the wreck in September 2008. Owing to the combined effects of tide and shifting sand, the poor old Dornier was lying upside-down on a bed of chalk.

Rather surprisingly, this mostly-intact wreck is the only one of 1,500 original Dorniers that still remains. Obviously, it's of some historical interest, so a plan was drawn up to pluck the bomber off the sea floor.

The first step in the recovery operation was to determine exactly what bits were left, and what condition they were in. Side-scan sonar and magnetometer surveys were conducted. A multibeam echo sounder is used to build up a surprisingly detailed 3D model of the plane and surrounding seabed.

Next, divers from the RAF Museum and Wessex Archaeology conducted a physical swimming-round-and-poking-it survey, to work out which bits of the plane were still structurally sound, and which were waiting to crumble away at the faintest touch. A few minor artefacts were picked up, and a plan drawn up.

Roll forwards a few years, and with the funding in place, the RAF Museum contracted salvage experts SeaTech to do the (literally) heavy lifting. In conjunction with chemists and physicists from Imperial College London, who assisted in determining the structural integrity of the aircraft, it was determined that just whacking some loading straps round the plane and hitting 'go' on the winch would be a bit of a non-starter.

Instead, an aluminium lifting frame was to be assembled around the upside-down plane, to take the load. From the beginning of the salvage operation, though, things didn't quite go to plan. May was a pretty terrible month for weather (as we all probably remember fondly, sitting in our offices sweating away the mid-summer pounds); as a result, the salvage team had to return to port on four separate occasions.

All those delays took a fair chunk out of the budget for the project, and by late May, the plan was changed. Instead of the aluminium lifting frame, the salvage divers inserted a spar down the centre of the Dornier, attached lifting points to the strongest parts of the remaining structure, and lifted the aircraft as one single piece in an hour-long operation. The engines will come up at a later date.

The restoration effort began as soon as the plane was landed on the salvage barge. Rinsed off with fresh water and with a jelly-like substance applied to delay corrosion, the Dornier was taken to its new home at Cosford.

There, in two specially-constructed poly tunnels, any remaining salt water was rinsed away, and a mixture of chemicals applied to prevent any further damage. It's the same method used for the Mary Rose when she was dragged out of the Solent, but a new technique for aircraft.

The exact blend of chemicals was determined by scientists from Imperial College London. Based on tests from samples of the Dornier they've already been working on, a mixture of citric acid and sodium hydroxide was initially used; however, it's an on-going process, and the chemicals will be collected after they've been applied to the Dornier, and re-analysed to see if the process is working as intended.

A few other challenges remained. Of course, this being Health & Safety Britain, a risk assessment had to be carried out to ensure that the wreckage was safe to work on. Unsurprisingly, on a war plane, an ammunition magazine was found, the Army bomb squad called out, and the offending article X-rayed, and found to be empty.

After that, the Dornier was split -- gently -- into segments, so that the restoration work could begin properly. The ultimate aim is to have the Dornier restored and on display at the RAF Museum in Hendon; for now, the restoration work can be seen live at the RAF Museum in Cosford (which is well worth a visit in its own right).